The present invention relates to an electronic still camera that converts an optical image formed by an optical system into an electronic image signal with a solid state image sending device having a CCD (charge coupled device) and related components, and the resulting electronic image signal is recorded on a recording medium such as a magnetic disk.
An electronic still camera which converts an optical image into an electronic image signal and records the electronic image signal on a recording medium such as a magnetic disk is disclosed in U.S. Pat. No. 4,057,830, U.S. Pat. No. 4,366,501, U.S. Pat. No. 4,599,657, and U.S. Pat. No. 4,783,707. In a prior art electronic still camera of this type, the magnetic disk is driven by a DC motor or the like. Since, therefore, the power consumption of the camera is large, the battery cannot be used for a long time. In order to use the battery for the longest possible time, the following method has been proposed by the prior art. In a single mode, wherein only one still image is recorded, the motor is started each time the shutter switch is operated and is stopped after the corresponding still image is recorded. In a continuous mode, wherein a number of still images are successively recorded at predetermined time intervals, the motor is started in synchronization with the start of the operation of the shutter switch. Then, while the shutter switch is being operated, the motor is kept driven and a number of still images are recorded at predetermined time intervals. When the operation of the shutter switch is stopped, the motor is stopped.
However, the above method is disadvantageous for at least the following two reasons: First, it is likely that the shutter switch will be kept operated even after a still image is recorded in all recording areas of the recording medium. Since the shutter switch is likely to be kept operated nevertheless, the motor is maintained in a driven state and power is wasted. Second, if the motor is kept driven, the user may be led by the resulting sound to mistakenly think that the camera is recording a still image on the recording medium even after this recording is actually finished.
To solve these problems, the prior art provides a mechanical switch or the like at a position in the vicinity of the last one of the recording areas of the recording medium. The mechanical switch detects a recording head if this recording head comes to the recording position, and simultaneous with this detection, the entire still camera is automatically turned off.
Although this method solves the problems mentioned above, it gives rise to the following inconveniences and shortcomings. The user has to operate the power source switch to turn on the camera each time he or she uses the camera. Let it be assumed that the camera has a monitor display capable of showing a still image recorded on the recording medium. If the mechanical switch automatically turns off the power source, when the monitor display is again powered up it cannot immediately show the still image. Also, the method is disadvantageous in the case where the recording medium has a free storage area preceding the storage area on which the first still image is to be recorded in the continuous mode. In this case, a still image cannot be speedily recorded on the free storage area after the recording of still image data is finished in the continuous mode. It should be further noted that an electronic still camera requires initial processing after the power source is turned on. For instance, the electronic still camera has to detect whether or not the recording medium is located at the predetermined position, and to move the recording head to the predetermined position. In other words, a finite time is required for the electronic still camera to be set in a standby condition after the power source is turned on. Therefore, if the power source of the electronic still camera is turned off, as in the method noted above, the user has to wait for the initial processing to be completed after he or she turns on the power source again.